Such devices are suitable, in particular, as fastening means for racks, stands, rod constructions, three-dimensional frame constructions, as well as for surgical fixation devices.
The EP-Patent No. B 0 700 664 discloses a device, for which four separate jaws, mounted on a shaft, define two openings, into which fastening rods or bone pins can be introduced against the force of a spiral spring positioned between the pair of jaws. The large number of individual parts and their slight flexibility or adaptability to the geometry of the building components, which are to be introduced into the openings, is a disadvantage of this known device.
U.S. Pat. No. 5,727,899 of DOBROVOLNY discloses a device with two clamps, which, however, are not intended for an external fixator. Admittedly, this known device enables a longitudinal carrier to be snapped in latterly, however, only into one of the two clamps. However, this snapping in does not take place due to the elastic deformation of the clamp, nor does it take place against the pressure of a spring, which is disposed between the two clamps. Instead, this snapping in requires a separate spring, which is disposed in the opening of the clamp. The transitions (fulcri), which act as pivot joints, are mounted between the openings of the clamps and the fastening ends, so that, when the fastening ends are expanded by means of the lever 90, the clamp openings close, clamping the longitudinal carrier located therein. For this purpose, the clamps have an H shape. The fulcri are between the openings of the clamp and the fastening ends. The following are further disadvantages of this known device:
a large number of individual parts
a complicated and expensive installation
complicated and difficult cleaning
and only rods of a certain diameter can be accommodated.
U.S. Publ. Appln. No. 2002/0151892 of WALULIK ET AL. discloses a generic device. A first embodiment relates to two-piece clamps and a second embodiment relates to elastically deformable clamps, which are constructed in one piece and in such a manner, that they can be pressed together completely coaxially with the central shaft. For this purpose, the clamps are positioned without clearance on the central shaft.